U.S. Pat. Nos. 5,443,083; 5,381,819; and 5,890,512; each of which is incorporated herein by reference, disclose a number of regulator designs for use in CNG service. Each of these applications also names as either the sole inventor or as a co-inventor, Jeffrey Gotthelf, the inventor of this application. Each of these designs has many elements that are similar to elements of the regulator design of the present invention.
Coalescing filters are commonly required in CNG lines upstream of the pressure-reducing regulator to protect the regulator from entrained oil. Although one or more of the designs disclosed in the above references include particulate filters, particulate filters typically cannot remove entrained oil. Over time, entrained oil may foul the regulator and inhibit its performance. The need for upstream coalescing filters requires additional cost and takes up space in existing fuel systems, and with each connection also creates additional risk of gas leakage.
Regulators having flow bypass designs (where the gas flow does not flow through the diaphragm chamber) with improved transient response characteristics are desirable, as is reduction of output pressure overshoot when inlet pressure is suddenly applied. It is also desirable to provide shock absorption in the element that connects the diaphragm assembly to the valve element.